There were 7 open NFL head coaching positions when Josh McDaniels announced that he would not be available to interview for any of them. Some people in Boston took that as evidence that McDaniels is somehow going to replace Bill Belichick as the next coach of the New England Patriots. After thinking about it - I think the answer is just a whole lot simpler than that.
Josh McDaniels is just happy where he is.
McDaniels gets to coach one of the top 3 QB's in NFL history. He gets to learn from one of the top 3 coaches in NFL history. And the guy who signs his paychecks just may be the best owner in all of professional sports - Robert Kraft. Throw in the fact that McDaniels is probably very well paid by the Patriots and that the team is perennial Super Bowl contenders - why would McDaniels want to change from that?
Also consider that if McDaniels did interview and get an NFL job - no matter what job it was at least 50% of the fan base would say they wanted someone different. Then you'd have the Tim Tebow speculation. There would be a deluge of "should or will McDaniels trade for Tebow" talk. Finally - McDaniels is not in a position to demand a long-term deal or demand years of runway space to get "his" program going. In New England he can stay as long as he wants.
Why would Josh McDaniels interview for any of those open NFL teams?